So, first the answer, and then I'll provide some more observational goodies...
Think back to the Sequel Trilogy. When Rey healed Ben Solo, he wasn't dead. He was still alive - mortally injured, but alive. In ANH, we saw Ben Kenobi heal Luke after he had been assaulted by Sand people AND there is also mention in legends of the "Jedi Healers."
Rey only ever healed.
Kylo Ren brought Rey back from the dead. She had crossed over completely. Wait, wasn't her body supposed to vanish? Being a Jedi? No, and that's because I believe that the Skywalkers are of a certain cosmic force energy that renders them incorruptible on the spiritual plane. Anakin didn't die a sith, and neither did Ben Solo. The Netherworld of the Sith cannot have their souls, and they probably want it. But then, there's the pothole of how we've been able to see Ani's ghost in RotJ (in the newer GL edited version) yet Ani's body didn't vanish. Strange...
Now here's something to consider...
With regard to the sequels, and the RoS in particular...
There's so much meta, the sequels I would argue are a love letter to the OT and the Prequels. In that, Ben Solo represents the OT and Rey the PT. "Two were made, to strengthen the one." The one (what is perceived as the evil emperor, the hated) (the sequels) is the summation of the first two. It contains the essence (force) of both into something we never truly understood (new mega powerful emperor/sequel). What we do see, is that Ben Solo is proof that the Skywalker line is incapable of ever completely succumbing to the Dark in damnation to Death. The Sith Netherworld will never claim a skywalker. We see that he, like his grandfather, is good at fixing things. He never gained the complete cost-free knowledge his grandfather sought (immortality), but he did learn how to save others. But it came at a cost to him, and he chose to pay that cost, as his uncle chose to pay the cost of buying time for the rebellion to escape Kylo Ren.
Kylo Ren/Ben Solo is the main character of the Sequel. Not Rey. Check out this video that in a theatrical edit kind of way, shows how much Ben/Kylo is like his uncle and his grandfather, Ani. It's worth it if you like OT/PT.
https://www.youtube.com/watch?v=5eQmk_GR59I
There's so much more to analyze too, if you're interested.
